The neutrino burst from SN1987A were detected by KAMIOKANDE and also IMB in February this year. The neutrino events detected by KAMIOKANDE were clustered into three bunches; event number 1-5, 7-9, 10-12. The first two bunches of the neutrino events can be understood by the standard scenario of supernova explosions.
However, it is very difficult to explain the last bunch of the neutrino events by the standard scenario, especially the total energy of the neutrinos and the radius of the neutrino sphere; it is necessary at least several times of 1052 ergs to explain the total energy of the last three events. In order to explain this energy, we must consider the non-standard mechanism of the neutrino emission.